


Surprise

by thelonelywriter



Category: Supernatural
Genre: Alpha Dean Winchester, Alpha/Beta/Omega Dynamics, Anal Fingering, Anal Sex, Beta Sam Winchester, Bottom Castiel, Claiming, Fallen Angel Castiel, Kitchen Sex, Knotting, Love Confessions, M/M, Mating Cycles/In Heat, Omega Castiel, Plot What Plot/Porn Without Plot, Rough Sex, Shameless Smut, Smut, Top Dean
Language: English
Status: Completed
Published: 2016-05-07
Updated: 2016-05-07
Packaged: 2018-06-07 01:07:09
Rating: Explicit
Warnings: No Archive Warnings Apply
Chapters: 1
Words: 3,379
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/6778822
Author URL: https://archiveofourown.org/users/thelonelywriter/pseuds/thelonelywriter
Summary: <blockquote class="userstuff">
              <p>Once Castiel has fallen from Grace, Dean suspects him to present like everyone else does. But, after a few weeks with no result, Dean figures that he just won't present. He's proven very <i>very</i> wrong when Castiel goes into heat.</p>
            </blockquote>





	Surprise

**Author's Note:**

  * For [EllaWinchester24](https://archiveofourown.org/users/EllaWinchester24/gifts), [rieraclaelin](https://archiveofourown.org/users/rieraclaelin/gifts).



> Alright, so this is my first A/B/O fic so please, please take mercy on me, I only know so much!! I'm gifting this to both EllaWinchester24 and rieraclaelin because it was the ever wonderful rieraclaelin that told me what I needed to know about A/B/O and I'm also gifting this to the constantly lovely EllaWinchester24 because I know that she likes A/B/O and I know that she's been down lately!! So, I hope that you guys like this!!

Dean figured that after Cas fell from grace and became human that he would present just like everyone else, alpha, beta, omega. To his knowledge angels didn’t have that system, but he figured that once Cas was no longer an angel he would have to deal with regular human things including the alpha, beta, omega system. But, as the weeks went on and Dean continued to help him out with the whole getting used to being human thing and nothing happened, Dean figured that maybe he just wasn’t going to present as anything, maybe he was off the hook because of the way he had been built or something. So, he figured that there was nothing to worry about, that he should stop indulging in those stupid fantasies where Cas happened to be an omega and Dean could actually knot him. But, there was a surprise in store for Dean.

They were on a regular hunt, a vamp hunt, and everything was going as per usual, Dean was doing his best to not admire just how sexy Cas looked when he had blood splattered over him and a machete in his hand. And then he smelled it. It started out soft at first, like a Spring day, like flowers, Dean’s favorite kind. Dean tried to ignore it at first but then he couldn’t help but pause to sniff the air. God, where was that coming from? They were in the middle of a huge nest of vampires, it should have smelt like blood, not, not fresh air and clean water.

Dean was so busy getting lost in the smell that he almost got his head handed to him by a vamp who came at him from behind. He managed though, and in the end everything went well, no one died, so that was a plus. Sam noticed Dean’s little, whatever you would call it, however, and he picked up on it. “Dude, what happened there? You looked like you were just standing there smelling the air,” Sam said, looking over at Dean with a perplexed look. Dean just waved his hand dismissively. 

“Just got a little distracted, that’s all,” Dean replied, continuing to speak so that Sam didn’t keep after him on the whole matter. “Who’s hungry?”

\---

The three went out to a diner after the hunt and the scent never left the air the whole ride there. It only got worse, if possible, when they were all sitting down eating. Dean was completely vexed. He tried to ignore it the whole way back to the motel but it was so Goddamn hard to ignore. Dean had no explanation behind it even when they got back to the motel.

Sam was the first one out of the car leaving Dean and Cas alone in it, and then Dean finally decided to speak up. “Do you smell that?” Dean inquired and Cas paused, sniffing the air.

“What does it smell like?” he questioned. Dean shook his head.

“It just smells, I don’t know, good. Really good,” Dean went on. Castiel paused again and shook his head.

“I don’t smell it,” Castiel informed Dean who sighed, getting out of the car.

“Well, get some sleep tonight. It’s a long drive back tomorrow,” Dean told Cas as he closed the door to the Impala and began walking towards the motel rooms.

\---

Dean realized the next day when everyone got in the car what was happening. He had gotten a good look at Cas and that was one of the cues that led him to his conclusion. Cas was finally presenting and he was presenting as an omega. And he was in heat. Dean could tell by looking at him, his eyes were fractionally wider and brighter than usual, his hair was a little more messy, Dean could practically feel his heart beating faster just from being in the same vicinity as him. Apparently, the day before Cas had just been going into his heat because the next day was awful. That smell got twenty times worse. Dean had smelled a fair amount of omegas in heat but none of them smelt as good as Cas. Cas smelt like everything that Dean could have dreamed of, every wonderful scent there was out there. Dean could feel the heat radiating from his body all the way from the front seat of the Impala. Dean swore he was gonna pop a boner at any second if Cas got even marginally closer to him.

Dean could barely stand it, but he knew that he had to. He couldn’t just fuck Cas, Cas was his best friend. And the one he had had a crush on since they first met but that was beside the point. Cas obviously just thought of Dean as a good friend so Dean couldn’t just go shoving his dick inside of Cas because that would make things… awkward.

Typical beta Sam didn’t even notice or smell a thing, but Dean could smell and notice every single thing about Cas’ heat that there was to notice. And he dealt with it the whole ride back to the Bunker. He figured that he’d be safe there, that Cas would maybe lock himself in his room and Dean would do the same in kind, but no. No, there were other plans for both of them.

Dean knew that Cas was nearing the end of his heat a few days later and Dean thought that maybe he would actually survive it and then find some sneaky way to toss a bottle of heat suppressants Cas’ way because there was no way that Dean was going through that again. But then, one morning, both Cas and Dean were in the kitchen, Sam researching in the library. Dean was gritting his teeth and doing his best not to shove Cas up against a wall and mark him damnit because Dean wanted Cas, he wanted Cas to be his, his mate, just _his_ , he wanted Cas to belong to him. Dean was in the midst of trying not to think those thoughts when he dropped his cup of coffee. He swore under his breath, immediately going to grab some paper towels but Cas apparently had the same thought because soon their hands were touching as they both reached for the paper towels and their bodies were mere inches apart. Dean couldn’t stop the soft groan that fell from his lips.

Cas was so fucking close, Dean could feel the heat of his body, he could smell that intoxicating smell that was practically strangling him at this point. It was just Cas and all Dean could think was _Fuck, knot, mate, fuck, knot, mate_ , and it was driving him off the fucking wall and he was actually trembling a little because he was trying so hard not to jump Cas and rip off all those pesky layers of clothing. Dean wasn’t the only one trembling though. Dean was looking at Cas’ hand because he could definitely not look him in those needy, lust blown eyes. “I’m in heat,” Cas stated, his voice trembling just like his hand. Dean had to bite back another groan.

“You think that I haven’t noticed?” Dean said, trying to keep his own voice steady. He could practically feel Cas swallow next to him.

“You’ve done a good job of resisting me,” Castiel went on.

“You’re my friend, Cas, I’m not gonna, y’know, do anything with you.”

“I want you to.”

Dean almost choked on his own spit when those words came out of Cas’ mouth. But then he had to rationalize things. Cas was in heat, he would beg anyone to knot him, Dean was just another guy, another random person who could knot Cas. “Cas, you’re saying that because you’re in heat,” Dean sighed, taking his hand away from where it had been and placing it on the counter.

“I’m saying it because I’ve wanted you to ever since I pulled you from Hell,” Castiel said, his voice reverent. Dean froze. That didn’t sound like the heat talking.

“Woah, woah, woah, what are you talking about?” Dean inquired, finally turning to look at Cas.

“I’ve wanted you ever since I pieced your soul back together and I never said anything because I didn’t think that you’d feel the same way,” Castiel explained quickly as though his words were invalid and Dean was going to laugh at them. But Dean did everything but laugh at them.

“You’re, you’re being serious, you’re not just saying that,” Dean murmured in disbelief. Castiel bit his lip and shook his head. “You really want this?” Dean inquired, and Castiel nodded hurriedly, looking up at Dean with those pleading blue eyes. And that was just _it_. Dean pushed forwards, slamming Cas into the nearest wall with a thud that had the dishes rattling in the sink. Dean’s breathing turned jagged as he simply looked over Cas’ features, his eyes settling on those pretty pink lips that Dean did not hesitate to press his own to.

It was less than a second into it when Cas had parted his lips, letting Dean’s tongue slide into his mouth. Dean let out a low groan at the taste of Cas. Fuck, Cas tasted even better than he smelt. The kiss was sloppy, there was no time to be precise, even though in Dean’s mind, in the times that Dean had imagined fucking Cas, kissing Cas, doing anything with Cas he always imagined taking his time, being so sweet with him, licking open his mouth so slowly until Cas was whining for more. But fuck that, right now Dean just needed his dick inside of Cas as quickly as possible.

Dean immediately stepped out of his shoes and socks, his hands that were sliding over the fabric of Cas’ t-shirt, over his chest, sliding down to undo the button and zipper of his own jeans. Dean kissed Cas until Cas could barely breathe and Dean had to pull away. “More, need more,” Castiel panted as Dean tugged off his own shirt.

“Don’t worry, I got you,” Dean soothed, encouraging Cas to tug off his own shirt too. Cas kicked off his own shoes and socks, welcoming Dean as he pressed forwards, grinding their hips together with a moan. “Fuck, Cas, want you so much,” Dean panted, mouthing hotly over Cas’ neck.

“Need you,” Castiel panted right back, his hold grappling on Dean. Dean groaned, using all his strength to actually step away from Cas so that he could get out of his jeans and his boxers. Cas was obviously on the same page because he did the exact same thing once he had enough room to. And finally, the two of them were naked, Dean’s eyes raking over Cas’ nude form, catching on the sight of his cock, hard and leaking against his stomach. Dean licked his lips. He definitely had to do something about that. 

“Table, bend over,” Dean ordered simply, and Castiel hurried to comply, heading straight over to the table and placing his palms on it, spreading his legs oh so obediently, enough to make Dean even harder than he already was. Dean walked over to Cas, slipping a hand around his hip, glancing down to catch the slick that was trailing down Cas’ thighs. Dean could smell it and it was even better than Cas’ usual smell. It almost made him dizzy. 

Cas could feel Dean’s eyes on him and he arched his back, sticking out his ass and presenting just for Dean. Dean almost fucking lost it at that. “Fuck, Cas,” Dean grit out as he spread Cas’ cheeks, easily slipping one finger past his rim. Castiel let out a little gasp at the intrusion, and that brought Dean to a thought. “You’ve never, have you ever, y’know, done this before?” Dean inquired, and Castiel blushed, hanging his head and shaking it. Something hot erupted in Dean’s belly at the thought. He was going to be the first one to be inside of Cas, he was going to be the first one to knot him, to fuck him. Dean let out a soft groan, slipping a second finger in with the first. “Don’t worry, I’m gonna take good care of you,” Dean soothed, still rubbing one hand over Cas’ hip. He could feel and see Cas visibly relax underneath him, and the sight made his heart warm.

Dean fucked those two fingers in and out of Cas, scissoring him open and doing his best not to fucking faint at the scent of Cas’ arousal, his slick. He soon slipped in a third finger, making sure not to rush but still going as quick as he could since after all, he had been wanting this for years and now that he was finally getting it it was like a fucking dream come true.

Dean stretched Cas until he was sure that he was stretched enough, and then he gently nipped at Cas’ neck. “You ready?” Dean questioned softly despite the fact that he wanted to fucking growl out the filthiest things in Cas’ ear. Castiel nodded and a rush of heat made its way through Dean. Dean shifted a bit, telling himself in his head that he would go slow, that he would ease his way in. Out of instinct he instead slammed into Cas so hard that Cas was jolted forwards with another gasp. “Sorry, meant to go slower,” Dean grit out as he circled his hips a few times, trying to let Cas get a feel for things. Castiel let out a breathy moan, shaking his head.

“No, want it rough,” he breathed out, and boy did that get Dean going.

“You sure?” Dean double checked before he full out slammed into Cas once more. Castiel nodded eagerly, turning his head, his lustful gaze catching Dean’s. 

“Please,” he said, and his tone sounded so broken that Dean could barely stand it. He pulled out and slammed back in, jostling Cas forwards once more. Castiel moaned again, widening his stance. Dean caught the action and bit back a groan as he started up a rhythm, one that was rough and fast and dirty and everything that either of them could have wanted. Dean kissed up Cas’ neck, sucked and licked and bit; no claiming bite though, not yet, he wanted to wait for that, wait for the right time.

“God, Cas, drove me fucking crazy. Smelled so good, could practically taste you. Wanted you so bad,” Dean panted in between harsh sucks into Cas’ fair skin. Castiel eagerly bared his neck for Dean, shoving his hips back into Dean’s.

“Wanted you too. Wanted you so so bad for so long, Dean,” Castiel choked out. Dean groaned, nuzzling his head into the crook of Cas’ neck and taking a deep breath of the wonderful smell that resided there.

“Fuck, you’re so good, Cas, so perfect,” Dean praised, and Castiel moaned softly in response. Dean ate up the noise, plastering his body completely over and to Cas’, Cas’ back pressed to Dean’s chest, not an inch of them feeling separate. The sound of their hips smacking together echoed throughout the kitchen along with a rumbling low growl that Dean soon recognized to be coming from him, soft moans and little hitched breaths falling from Cas’ lips. “God, you feel so good, so fucking tight,” Dean grit out as he thrust desperately into Cas as though the fate of the world depended on it. Castiel let out a little moan in response and Dean groaned, nipping at his neck. Dean was trying not to get territorial about this whole thing since after all Cas had _just_ confessed his feelings to Dean and Dean didn’t want to go claiming Cas when they had barely talked this whole thing over but that didn’t stop his natural biology from growling, “Mine, you’re mine, Cas,” right into Cas’ ear. Cas seemed unaffected though, all he did was reply with a breathy,

“Yours, all yours, want to be yours.” It made fire rush through Dean, a hot sensation that he hadn’t felt in awhile coming over him. The need to claim, to mate, to knot. Cas was his, he had to be his, there was no other way things could be. And Cas definitely sounded like he knew what he was talking about despite the whole heat thing. Dean was beginning to wonder if Cas really did want this as much as Dean did.

It was then that Cas cried out, clenching around Dean and eliciting a wonderful groan from him. It took him a second, but he realized just what he had hit. “Right there?” Dean murmured, and Castiel nodded hurriedly. 

“Yes, please, Dean, more, need more, want more,” Castiel breathed out. Dean nipped and kissed along his neck, his hands moving to cover Cas’ so that their fingers could interlace. This was it, Dean thought, this was Heaven. This was pure and wonderful and magnificent, he thought as he sped up his thrusts and pounded into Cas as hard as he could. He had never dreamed that sex could be so perfect, so wonderful. It all came together, it all came together with one big bow on the top. Cas begging and panting underneath him with his legs spread and his ass out, back arched. It was perfect. It was a display for Dean, just for Dean, one that only Dean got to see. It made everything inside of Dean swell in this wonderful warmth. 

Dean could already feel himself getting close, he could already feel his knot swelling, and by the looks of it, Cas was on the same page. “You close, angel?” Dean muttered into Cas’ ear.

“Yes, fuck, yes, please Dean, knot me, need you to knot me,” Castiel begged and God if Dean wasn’t already gone then there he went because that was the hottest thing he had ever heard come out of Cas’ mouth and it was directed right towards him.

“Don’t worry, I got you, I got you,” Dean reassured him. “Can’t wait to see you come, Cas, fuck, you’ll look so gorgeous. You gonna come on my knot alone?” Dean grunted, and Castiel nodded frantically.

“Yes, yes, promise,” Castiel panted, his hips shoving themselves into Dean’s at a desperate rhythm. 

“Good,” Dean replied as he licked a stripe up Cas’ neck, tasting the salty sweet skin there. He was thrusting into Cas even harsher by now, his thrusts erratic as his knot swelled more and more with every passing second. Cas could feel it and the fire inside of him began to grow, fanning out to every limb, every nerve that he had, and it only took a few more thrusts before he felt that heat explode, and he let out a wail as he clenched around Dean, his hands squeezing Dean’s tightly.

Dean groaned at the sight, growling as he thrust in a few more times before he was coming, a claiming bite left on Cas’ neck as he buried himself deep inside of Cas. Both Dean and Cas felt a buzz of electricity when Dean’s teeth closed around Cas’ neck, and it only made the highs of their orgasms more enjoyable.

Dean finally pulled his teeth away from Cas’ neck, nuzzling his head into the crook of Cas’ neck when he had. The two panted for a moment, letting their breathing return to normal before Cas spoke. “I meant everything that I said, I hope that you know that,” he breathed out, still trying to get his heart rate to return to normal. Dean smiled softly, pressing a kiss to the bite left on Cas’ neck.

“Yeah, I do.” There was another silence before Dean went on. “I did too, y’know.”

“Yeah, I know,” Castiel replied with a soft little smile as he turned to get a glimpse of Dean. Dean smiled back at him.

“Good,” Dean replied. Another pause graced the air. “So, you’ve really had feelings for me all these years?” Dean inquired shyly. Castiel sighed and nodded.

“Yeah, I have. And you have too?’

“Pretty much.”

“Well, I guess that we’re both blind idiots then,” Castiel said, turning to Dean with a grin. Dean grinned back at him.

“Yeah, I guess we are.”

**Author's Note:**

> Tell me what you guys thought!! Maybe you want more A/B/O or maybe you like my other fics, or even both, who knows!!! My tumblr is [over here](http://ughcas.tumblr.com) in case you want to be my friend or send me something, whatever you'd like :) Thank you guys so so much for reading, I hope that all of you are doing well <3


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